The invention relates to improved apparatus for the production of a treatment bed made up of solid particles to be partially submitted simultaneously to a fluidisation action and to an at least horizontal circulatory movement.
It is known to use fluidised beds of solid particles for carrying out various treatments of granular products, such as drying, coating, oxidation or firing; fluidised beds are also used in various granulation processes. In all these processes, it is desirable that the solid particulate product constituting the fluidised bed should be subjected to a circulatory movement which moves the granular products from one end of the fluidised bed where they are fed in to the other end where they are recovered. A circulation of this kind may be effected, for example, by using the process described in our French Pat. No. 2,238,532, by means of which the desired circulation can be obtained without the solid particles which constitute the fluidised bed leaving the apparatus. According to a particular embodiment of this process, a parallelepipedal enclosure is used which is subjected to vibrations and comprises two non-fluidised lateral zones. The vibrations set up circulating currents in these lateral zones, which transport the solid particulate products towards one of the ends of the fluidised bed, where the accumulation of these products causes a reverse circulation in the fluidised zones.
However, an apparatus of this kind has the disadvantage that it cannot be extended at will. In practice, there is a maximum width for the fluidised zone which must not be exceeded and, for apparatus of larger dimensions, a number of juxtaposed fluidised beds have to be used, which makes the apparatus more complicated and thus more expensive.